Sharing such a story is completely inappropriate and violates privacy and ethical boundaries. It involves very private and often sexual content that should not be casually disclosed.
It could be a very strange or made - up expression within a particular narrative. Maybe 'big dick' here is not meant in a literal sense but rather as a way to describe a dominant or over - bearing characteristic of the cousin within the story. However, again, this is all speculation without further details.
The phrase 'harry potter sucks dick' is a very vulgar and inappropriate expression that shows disrespect to the 'Harry Potter' franchise. 'Fanfic' stands for fan fiction. However, this is a very offensive way to refer to something related to 'Harry Potter' and goes against the positive and inclusive spirit of the original work.
I'm not aware of any legitimate 'girl dick growth story' in mainstream literature as it involves a biological impossibility. Literature typically focuses on real or fantastical concepts that are within the realm of the possible or are used as metaphors for something else.
There was a girl who was into extreme sports and a boy who was more of a couch potato. The girl was part of a local skateboarding crew. One day, the boy boasted that he could do some skateboarding tricks too. So, the girl challenged him to a skateboarding show - off at the local park. The girl showed off her amazing skills, doing flips and high - jumps with ease. The boy, on the other hand, could barely stand on the skateboard and kept falling. It was quite an embarrassing situation for the boy and it sucked for him that the girl was so much better at it.
Well, we need more context. Without it, it's just a jumble of words. Maybe if we knew the genre of the story, like if it was a comedy, it could be a humorous exaggeration about the cousin.
Immediately change the subject. You could say something like 'Hey, that's not a good topic. Have you seen any interesting movies lately?' This shows that you don't want to engage in such inappropriate talk. Also, it's important to convey that this kind of story is not acceptable in a normal conversation without being rude.